1// Copyright 2014 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//go:build dragonfly || freebsd || linux || netbsd || openbsd
6// +build dragonfly freebsd linux netbsd openbsd
7
8package unix
9
10import "unsafe"
11
12// fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
13// systems by fcntl_linux_32bit.go to be SYS_FCNTL64.
14var fcntl64Syscall uintptr = SYS_FCNTL
15
16func fcntl(fd int, cmd, arg int) (int, error) {
17	valptr, _, errno := Syscall(fcntl64Syscall, uintptr(fd), uintptr(cmd), uintptr(arg))
18	var err error
19	if errno != 0 {
20		err = errno
21	}
22	return int(valptr), err
23}
24
25// FcntlInt performs a fcntl syscall on fd with the provided command and argument.
26func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
27	return fcntl(int(fd), cmd, arg)
28}
29
30// FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
31func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
32	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
33	if errno == 0 {
34		return nil
35	}
36	return errno
37}
38